Current conventional cancer treatments, i.e. surgery, radiotherapy and chemotherapy, are expensive, requires prolonged treatment period, and caused serious damage among cancer patients physically and psychologically. Compared to traditional treatment strategies, immunotherapy is characterized with autologous therapy, causing no damage to the body and a broad antitumor spectrum, particularly suitable for removing small amounts of residual tumor cells, especially dormant tumor cells which are difficult to eradicate by radiotherapy or chemotherapy.
Membrane vesicle is a vesicular structure generated by cells, in a diameter between 30-100 nm, with characteristics such as good stability, long-term storage, etc. It has been found in recent years that membrane vesicle deriving from dendritic cell is a biofilm structure which is suitable for immunotherapy. Many fundamental studies have shown that membrane vesicle produced by dendritic cells loaded with tumor antigens has good immunogenicity, and can effectively activate T lymphocyte cytotoxic response in vivo, kill the tumor cells and have long-term immunological memory. Clinical Phase I studies have shown that such membrane vesicles can effectively prolong survival time of cancer patients, and improve the survival rate of cancer patients, indicating that membrane vesicle can be applied to cancer immunotherapy.
However, there are certain concerns with respect to clinical applications of tumor immunotherapy, for example, firstly, the treatment course is complicated; secondly, the cost of treatment is high; thirdly, it is difficult to completely remove body tumor. To overcome these obstacles, a series of prophylactic tumor vaccines have been developed, such as the human papillomavirus (HPV) vaccine for preventing uterine cervix cancer and hepatitis B virus (HBV) vaccine for preventing liver cancer. However, targets of these prophylactic vaccines are relevant viruses causing tumor rather than the tumor itself, and they can only prevent occurrence of a single type of cancer, therefore there is a limited range of applications. Up to now no one has reported any clinical trials on non-viral prophylactic vaccine based on the tumor itself, or study on vaccine preventing the occurrence of multiple tumors simultaneously. As such, it is necessary to develop a new vaccine which targets tumor itself, and is capable of preventing the occurrence of a variety of tumors.